//! 插件系统核心实现
//! 
//! 实现了微内核架构的插件管理功能，包括：
//! - 插件接口定义
//! - 插件生命周期管理
//! - 插件依赖管理
//! - 插件热更新支持

use std::collections::HashMap;
use std::sync::Arc;
use async_trait::async_trait;
use serde::{Deserialize, Serialize};
use tokio::sync::RwLock;
use uuid::Uuid;

use crate::error::{KernelError, Result};
use crate::event::EventBus;
use crate::query::{Query, QueryResult};

/// 插件元数据
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PluginMetadata {
    /// 插件唯一标识
    pub id: String,
    /// 插件名称
    pub name: String,
    /// 插件版本
    pub version: String,
    /// 插件描述
    pub description: String,
    /// 插件作者
    pub author: String,
    /// 插件能力列表
    pub capabilities: Vec<Capability>,
    /// 插件依赖
    pub dependencies: Vec<String>,
    /// 插件配置Schema
    pub config_schema: Option<serde_json::Value>,
}

/// 插件能力枚举
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum Capability {
    /// 查询处理器
    QueryProcessor(QueryType),
    /// 数据连接器
    DataConnector(DataSourceType),
    /// 认证处理器
    Authentication(AuthType),
    /// 授权处理器
    Authorization(AuthzType),
    /// 缓存处理器
    Caching(CacheType),
    /// 监控处理器
    Monitoring(MonitorType),
    /// 脚本引擎
    ScriptEngine(ScriptType),
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum QueryType {
    Sql,
    GraphQL,
    Rest,
    FlightSql,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum DataSourceType {
    Sql,
    NoSql,
    ObjectStore,
    Stream,
    File,
    Api,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum AuthType {
    Jwt,
    OAuth2,
    ApiKey,
    Basic,
    Ldap,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum AuthzType {
    Rbac,
    Abac,
    Acl,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum CacheType {
    Memory,
    Redis,
    Distributed,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum MonitorType {
    Metrics,
    Tracing,
    Logging,
    Health,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum ScriptType {
    Sql,
    JavaScript,
    Python,
    Custom,
}

/// 插件状态
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum PluginStatus {
    /// 未加载
    Unloaded,
    /// 加载中
    Loading,
    /// 已加载
    Loaded,
    /// 运行中
    Running,
    /// 已停止
    Stopped,
    /// 错误状态
    Error(String),
}

/// 插件健康状态
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct HealthStatus {
    pub status: HealthLevel,
    pub message: String,
    pub timestamp: chrono::DateTime<chrono::Utc>,
    pub metrics: HashMap<String, serde_json::Value>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum HealthLevel {
    Healthy,
    Warning,
    Critical,
    Unknown,
}

/// 插件配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PluginConfig {
    pub enabled: bool,
    pub config: serde_json::Value,
}

/// 插件接口
#[async_trait]
pub trait Plugin: Send + Sync {
    /// 获取插件元数据
    fn metadata(&self) -> &PluginMetadata;
    
    /// 插件初始化
    async fn initialize(&mut self, config: PluginConfig) -> Result<()>;
    
    /// 插件启动
    async fn start(&mut self) -> Result<()>;
    
    /// 插件停止
    async fn stop(&mut self) -> Result<()>;
    
    /// 插件关闭
    async fn shutdown(&mut self) -> Result<()>;
    
    /// 处理查询请求
    async fn handle_query(&self, query: Query) -> Result<QueryResult>;
    
    /// 健康检查
    async fn health_check(&self) -> HealthStatus;
    
    /// 配置更新
    async fn update_config(&mut self, config: PluginConfig) -> Result<()>;
    
    /// 获取插件状态
    fn status(&self) -> PluginStatus;
}

/// 插件管理器
pub struct PluginManager {
    /// 已注册的插件
    plugins: Arc<RwLock<HashMap<String, Box<dyn Plugin>>>>,
    /// 插件状态
    plugin_status: Arc<RwLock<HashMap<String, PluginStatus>>>,
    /// 事件总线
    event_bus: Arc<EventBus>,
}

impl PluginManager {
    /// 创建新的插件管理器
    pub fn new(event_bus: Arc<EventBus>) -> Self {
        Self {
            plugins: Arc::new(RwLock::new(HashMap::new())),
            plugin_status: Arc::new(RwLock::new(HashMap::new())),
            event_bus,
        }
    }
    
    /// 注册插件
    pub async fn register_plugin(&self, mut plugin: Box<dyn Plugin>) -> Result<()> {
        let plugin_id = plugin.metadata().id.clone();
        
        tracing::info!("注册插件: {}", plugin_id);
        
        // 检查插件是否已存在
        {
            let plugins = self.plugins.read().await;
            if plugins.contains_key(&plugin_id) {
                return Err(KernelError::plugin(format!("插件已存在: {}", plugin_id)));
            }
        }
        
        // 验证插件依赖
        self.validate_dependencies(plugin.metadata()).await?;
        
        // 更新插件状态
        {
            let mut status = self.plugin_status.write().await;
            status.insert(plugin_id.clone(), PluginStatus::Loading);
        }
        
        // 初始化插件
        let config = PluginConfig {
            enabled: true,
            config: serde_json::Value::Null,
        };
        
        plugin.initialize(config).await.map_err(|e| {
            KernelError::plugin(format!("插件初始化失败 {}: {}", plugin_id, e))
        })?;
        
        // 注册插件
        {
            let mut plugins = self.plugins.write().await;
            plugins.insert(plugin_id.clone(), plugin);
        }
        
        // 更新状态
        {
            let mut status = self.plugin_status.write().await;
            status.insert(plugin_id.clone(), PluginStatus::Loaded);
        }
        
        tracing::info!("插件注册成功: {}", plugin_id);
        Ok(())
    }
    
    /// 启动插件
    pub async fn start_plugin(&self, plugin_id: &str) -> Result<()> {
        tracing::info!("启动插件: {}", plugin_id);
        
        let mut plugins = self.plugins.write().await;
        let plugin = plugins.get_mut(plugin_id)
            .ok_or_else(|| KernelError::plugin(format!("插件不存在: {}", plugin_id)))?;
        
        // 更新状态
        {
            let mut status = self.plugin_status.write().await;
            status.insert(plugin_id.to_string(), PluginStatus::Loading);
        }
        
        // 启动插件
        plugin.start().await.map_err(|e| {
            KernelError::plugin(format!("插件启动失败 {}: {}", plugin_id, e))
        })?;
        
        // 更新状态
        {
            let mut status = self.plugin_status.write().await;
            status.insert(plugin_id.to_string(), PluginStatus::Running);
        }
        
        tracing::info!("插件启动成功: {}", plugin_id);
        Ok(())
    }
    
    /// 停止插件
    pub async fn stop_plugin(&self, plugin_id: &str) -> Result<()> {
        tracing::info!("停止插件: {}", plugin_id);
        
        let mut plugins = self.plugins.write().await;
        let plugin = plugins.get_mut(plugin_id)
            .ok_or_else(|| KernelError::plugin(format!("插件不存在: {}", plugin_id)))?;
        
        plugin.stop().await.map_err(|e| {
            KernelError::plugin(format!("插件停止失败 {}: {}", plugin_id, e))
        })?;
        
        // 更新状态
        {
            let mut status = self.plugin_status.write().await;
            status.insert(plugin_id.to_string(), PluginStatus::Stopped);
        }
        
        tracing::info!("插件停止成功: {}", plugin_id);
        Ok(())
    }
    
    /// 卸载插件
    pub async fn unregister_plugin(&self, plugin_id: &str) -> Result<()> {
        tracing::info!("卸载插件: {}", plugin_id);
        
        // 先停止插件
        if let Err(e) = self.stop_plugin(plugin_id).await {
            tracing::warn!("停止插件失败: {}", e);
        }
        
        // 关闭插件
        {
            let mut plugins = self.plugins.write().await;
            if let Some(mut plugin) = plugins.remove(plugin_id) {
                if let Err(e) = plugin.shutdown().await {
                    tracing::warn!("插件关闭失败: {}", e);
                }
            }
        }
        
        // 移除状态
        {
            let mut status = self.plugin_status.write().await;
            status.remove(plugin_id);
        }
        
        tracing::info!("插件卸载成功: {}", plugin_id);
        Ok(())
    }
    
    /// 获取插件列表
    pub async fn list_plugins(&self) -> Vec<PluginMetadata> {
        let plugins = self.plugins.read().await;
        plugins.values()
            .map(|plugin| plugin.metadata().clone())
            .collect()
    }
    
    /// 获取插件状态
    pub async fn get_plugin_status(&self, plugin_id: &str) -> Option<PluginStatus> {
        let status = self.plugin_status.read().await;
        status.get(plugin_id).cloned()
    }
    
    /// 验证插件依赖
    async fn validate_dependencies(&self, metadata: &PluginMetadata) -> Result<()> {
        let plugins = self.plugins.read().await;
        
        for dep in &metadata.dependencies {
            if !plugins.contains_key(dep) {
                return Err(KernelError::plugin(format!(
                    "插件依赖不满足: {} 需要 {}", 
                    metadata.id, 
                    dep
                )));
            }
        }
        
        Ok(())
    }
    
    /// 处理查询请求
    pub async fn handle_query(&self, query: Query) -> Result<QueryResult> {
        // 根据查询类型路由到相应的插件
        let plugins = self.plugins.read().await;
        
        // 这里简化实现，实际应该根据查询类型和插件能力进行路由
        for plugin in plugins.values() {
            if self.can_handle_query(plugin.as_ref(), &query).await {
                return plugin.handle_query(query).await;
            }
        }
        
        Err(KernelError::query("没有找到能处理该查询的插件"))
    }
    
    /// 检查插件是否能处理查询
    async fn can_handle_query(&self, plugin: &dyn Plugin, query: &Query) -> bool {
        // 简化实现，实际应该检查插件能力
        true
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::event::EventBus;
    
    struct TestPlugin {
        metadata: PluginMetadata,
        status: PluginStatus,
    }
    
    impl TestPlugin {
        fn new() -> Self {
            Self {
                metadata: PluginMetadata {
                    id: "test-plugin".to_string(),
                    name: "Test Plugin".to_string(),
                    version: "1.0.0".to_string(),
                    description: "A test plugin".to_string(),
                    author: "Test Author".to_string(),
                    capabilities: vec![],
                    dependencies: vec![],
                    config_schema: None,
                },
                status: PluginStatus::Unloaded,
            }
        }
    }
    
    #[async_trait]
    impl Plugin for TestPlugin {
        fn metadata(&self) -> &PluginMetadata {
            &self.metadata
        }
        
        async fn initialize(&mut self, _config: PluginConfig) -> Result<()> {
            self.status = PluginStatus::Loaded;
            Ok(())
        }
        
        async fn start(&mut self) -> Result<()> {
            self.status = PluginStatus::Running;
            Ok(())
        }
        
        async fn stop(&mut self) -> Result<()> {
            self.status = PluginStatus::Stopped;
            Ok(())
        }
        
        async fn shutdown(&mut self) -> Result<()> {
            self.status = PluginStatus::Unloaded;
            Ok(())
        }
        
        async fn handle_query(&self, _query: Query) -> Result<QueryResult> {
            todo!()
        }
        
        async fn health_check(&self) -> HealthStatus {
            HealthStatus {
                status: HealthLevel::Healthy,
                message: "OK".to_string(),
                timestamp: chrono::Utc::now(),
                metrics: HashMap::new(),
            }
        }
        
        async fn update_config(&mut self, _config: PluginConfig) -> Result<()> {
            Ok(())
        }
        
        fn status(&self) -> PluginStatus {
            self.status.clone()
        }
    }
    
    #[tokio::test]
    async fn test_plugin_manager() {
        let event_bus = Arc::new(EventBus::new());
        let plugin_manager = PluginManager::new(event_bus);
        
        let plugin = Box::new(TestPlugin::new());
        let plugin_id = plugin.metadata().id.clone();
        
        // 注册插件
        plugin_manager.register_plugin(plugin).await.unwrap();
        
        // 检查插件状态
        let status = plugin_manager.get_plugin_status(&plugin_id).await;
        assert!(matches!(status, Some(PluginStatus::Loaded)));
        
        // 启动插件
        plugin_manager.start_plugin(&plugin_id).await.unwrap();
        
        // 检查插件状态
        let status = plugin_manager.get_plugin_status(&plugin_id).await;
        assert!(matches!(status, Some(PluginStatus::Running)));
        
        // 停止插件
        plugin_manager.stop_plugin(&plugin_id).await.unwrap();
        
        // 卸载插件
        plugin_manager.unregister_plugin(&plugin_id).await.unwrap();
        
        // 检查插件是否已卸载
        let status = plugin_manager.get_plugin_status(&plugin_id).await;
        assert!(status.is_none());
    }
}
